Approximately 6% of all U.S. teenagers suffer from clinical depression which is known to result in continued risk for recurrences with persistence of depressive episodes and psychosocial morbidity into adulthood. MDD can have a serious impact on the lives of teens, by way of example: untreated depression is the number one cause of suicide, which is the third leading cause of death among teenagers. Given the magnitude of the problem, the U.S. Preventive Services Task Force, an influential government-appointed medical panel, urged doctors to routinely screen all American teens for depression. Traditional reliance on clinical assessments patient interviews and/or questionnaires for diagnosing MDD in a large population would require a large amount of resource and would be further limited in the frequency of application. Clearly better less subjective tools are needed to increase the caregivers'ability to identify MDD and other mood disorders within populations. Ridge Diagnostics is developing a test panel of blood based biomarkers (cytokines, stress related hormones, neuroendocrine and metabolic proteins) on physiological pathways related to MDD. Our preliminary clinical results suggest that our multiple marker test can effectively classify depressed patients and/or discriminate them from a normal population with a sensitivity of 87% and a specificity of 95%. The need to extend this aid to diagnosis to larger population screen requires quantitative, sensitive multiplex array technology which we are concurrently developing. This SBIR proposal will use Ridge Diagnostics biomarker panel for MDD and real-time detection to develop a minimally invasive, rapid real-time screening bioassay. PUBLIC HEALTH RELEVANCE: Depression (major depressive disorder, MDD) is the most common mental health disorder in the United States among teens and adults. MDD can have a serious impact on the lives of the many teens who suffer from depression. By way of example, untreated depression is the number one cause of suicide, and the third leading cause of death among teenagers. While about 6% of adolescents suffer from depression, between 10 to 15 percent of teenagers have some symptoms of depression at any one time. In addition it is estimated that 15 percent of teens with depression eventually develop bipolar disorder and 30 percent of teens with depression also develop a substance abuse problem. Depressed teens consistently under-report emotional issues to their teachers, family and friends, who often do not recognize the symptoms of depression, risk of suicide or substance abuse. The potential loss in life and productivity is so great, the U.S. Preventive Services Task Force, an influential government-appointed medical panel, urged doctors to routinely screen all American teens for depression. However, the potential economic burden of such a physician driven program is extremely large. Rather than using subjective evaluation tools, we propose to measure multiple analytes in blood as an aid to diagnosing MDD. The SBIR project will develop a cost effective, minimally invasive, rapid screening bioassay using a small volume of blood. An algorithm will be used to quantify the probability that a teen is suffering from MDD.